Political outsiders and opposition candidates have been the winners in Latin America in the past decade, and nowhere is that more apparent than in Mexico and Paraguay. Both voted out single-party systems that ruled their nations for most of the 20th century.

But now both countries are looking to vote back in the same systems they were so relieved to see fall just a few administrations prior.

When Mexicans head to the polls this Sunday, they are, according to surveys, expected to favor Enrique Peña Nieto of the Institutional Revolutionary Party (PRI), which had a grip on power here for 71 years until 2000. Then on the other side of the Americas the impeachment scandal surrounding Fernando Lugo in Paraguay, whose victory in 2008 broke 61 years of Colorado Party rule, has revealed deep dissatisfaction with his presidency. It has also highlighted the fact that the Colorados are poised to regain the presidency in 2013.

“[The Colorados] have won every single local election since they lost power,” says Juan Carlos Hidalgo, a Latin America analyst at the Cato Institute. “It's like the PRI of Mexico.”

In both countries, the rising popularity of the former ruling parties is a matter of expectations, which were sky high with the transition to democracy but deflated with the snail's pace of change. Some blame it on the inefficacy of new parties in power, others on the old power structures that are still deeply entrenched in both countries and that have blocked reform at every turn.

In both cases, it's given the old parties the chance to say: “We know how to do things, we are born to rule, you have to elect us back,” says Mr. Hidalgo. “It's pretty ominous. It means there is the case for having one party in government all the time.”

'A hard reality to swallow'

The latest polls in Mexico show that Peña Nieto has anywhere from a 10 to 17-point lead over his nearest rival, Andres Manuel Lopez Obrador, from the leftist Party of the Democratic Revolution. The conservative ruling party, whose ticket is headed by Josefina Vazquez Mota, is trailing behind both according to most surveys.

The PRI, which was once dubbed the “perfect dictatorship,” is widely accused of corrupt practices and cronyism during its reign. When it lost presidential elections in 2000, with the victory of the conservative National Action Party (PAN), the change in power was hailed across Mexico. So it comes as a surprise to some that after 12 years with the PAN in power, Mexicans are supporting the party they once feared they'd never be able to vote out.

But the PRI says it is a reformed party, one that is committed to democratic ideals of the 21st century. “It is the PRI of today,” says Eduardo Sanchez, the party spokesperson.

That is a hard reality for many to swallow, says Soledad Loaeza, a political analyst at the College of Mexico in Mexico City. “I think to many people it is very difficult to stomach the restoration of the PRI in power,” she says. “It is so closely associated to authoritarianism; it is like contributing to bringing back the past.”

Why the comeback?

So why is the PRI so far ahead? As is true in Paraguay, the “new” faces that emerged on the political landscape – in Mexico the PAN and in Paraguay Mr. Lugo – have been deeply disappointing. That is in part because of their own weaknesses. In Paraguay, Lugo was considered an outsider who would fight the graft that made the South American nation one of the most corrupt in the world, ranked 154th out of 183 countries in the 2011 Transparency International index. “This was one of his most fervent promises, but he has not gotten rid of corruption at all,” says Jose Maria Costa, a political analyst at the National University of Asuncion in Paraguay.

When he took office, his popularity was over 80 percent, according to Latinobarometro, the regional polling organization in Santiago, Chile. By 2011, his approval had fallen to 50 percent. It was not an issue of sluggish growth – for some of his years in office growth exceeded 10 percent. But he was unable to push through promised reforms, especially on land redistribution, the very issue that sparked his impeachment proceeding last week. Many in Latin America have said his ousting is a “break” with democracy. Lugo himself dubbed it a “parliamentary coup.” Others have defended the impeachment. In any case, analysts say, it has revealed a growing frustration with Lugo and the possible comeback of the Colorados in the next election cycle.

“It's very probable that the Colorados will win,” says Hugo Vera, the head of the Freedom Foundation in Asuncion, unless the opposition party now in power after Lugo's impeachment, does a formidable job over the next year, he says.

In Mexico, the PAN has held power for 12 years, a decade of disappointment, some say, which explains its weak position in the polls. The PAN has been faulted for sluggish economic growth that hasn't created enough viable jobs for the population. They have also been blamed for the deadly drug violence that has taken 50,000-plus lives in the past six years alone.

Some of the inefficiency might be due to inexperience – not the ultimate insiders who know the rules of negotiation and forging alliances, PAN members are political novices in many ways. But it's also the fault of the very same political machine that held power for so long.

In Mexico, for example, one of the major reforms most analysts agree needs to pass for the country to get ahead is energy reform. It's something that Peña Nieto has fully embraced on the campaign trail, but the PAN tried to pass similar reforms, only to be blocked by the PRI.

The same dynamic continuously played out during Lugo's term, says Peter Lambert, a Paraguayan expert at the University of Bath. He says that when the Colorados were in power, they tried to pass an initiative on personal income tax, but it was blocked. Once they were out of power, and the same initiative was on the table, the Colorados blocked it. “The opposition will look to block anything in terms of whether it will strategically help them to undermine the government,” he says.

In both countries “new governments have been ineffectual because they have been blocked at many steps along the way,” says Johns Hopkins Latin American expert Riordan Roett. In Paraguay, “while the [Colorados] were willing to yield to have the opposition in power, they made it almost impossible for Lugo to govern,” Mr. Roett says.

In other countries in Latin America where outsiders and opposition forces have won, like Bolivia, Ecuador, and Venezuela, for example, the old parties have practically become irrelevant as new presidents flatly rejected the traditional order. But in Mexico and Paraguay, the old players still hold tremendous sway, especially at the local and state levels. “Nobody should be surprised that the PRI is coming back to Mexico. The party apparatus didn't break down,” says Michael Shifter, president of the Inter-American Dialogue.